Reinforcement of Polyester with Renewable Ramie Fibers

Noan Tonini Simonassi,Jaroslaw Drelich,Frederico Muylaert Margem,Rubén Jesus Sánchez Rodríguez,Carlos Mauricio Fontes Vieira,Artur Camposo Pereira,Sergio Neves Monteiro,Janine Feitosa De Deus

doi:10.1590/1980-5373-mr-2016-1046

Abstract

Ramie (Boehmeria nivea) fiber is one of several lignocellulosic fibers with superior strength, but the least investigated, particularly as reinforcement in strong, tough polymeric composites. This paper presents mechanical properties for polyester reinforced with aligned ramie fibers up to 30% by volume. It was found that adding 30 vol% of ramie fibers increases the flexural strength of polyester about three times (212 ± 12 MPa vs. 63 ± 7 MPa) and tensile strength by a factor of two (89 ± 9 MPa vs. 53 ± 3 MPa). Polyester-ramie fiber composites also displayed a significant improvement in toughness. The impact energy values, as measured by Charpy and Izod impact tests, increased nearly two orders of magnitude for 30 vol% ramie fiber composite as compared to neat polyester. Additionally, fractographic studies revealed reasonable wetting of fibers by the polyester resin, and FTIR analysis confirmed a hydrophilic nature of ramie fibers. In spite of weak adhesion between hydrophilic fibers and hydrophobic matrix, composites of improved strength and toughness were demonstrated in this study. Limited fiber-matrix adhesion was reflected in preferential longitudinal propagation of cracks along the fiber/polyester interfaces, indicating also that most of the fracture area is associated with the fiber surface.

Highlights

Natural fibers extracted from plants, generally termed as ‘lignocellulosic fibers’, are presently considered engineering materials1 that constitute an environmentally appropriate alternative to replace more expensive, non-recyclable and energy-intensive synthetic fibers2,3
Despite attractive strength properties and numerous studies on reinforced composites21-43, little has been reported on the use of ramie fibers in polyester composites
A comparison between the average length of the ramie fibers in this work (L = 158 ± 69 mm) with its critical length lc = 1.6 mm, obtained from pullout tests39 indicates that these fibers should be considered as continuous (L > 15 lc) 44 for composite reinforcement

Summary

Introduction

Natural fibers extracted from plants, generally termed as ‘lignocellulosic fibers’, are presently considered engineering materials that constitute an environmentally appropriate alternative to replace more expensive, non-recyclable and energy-intensive synthetic fibers. Natural fibers extracted from plants, generally termed as ‘lignocellulosic fibers’, are presently considered engineering materials that constitute an environmentally appropriate alternative to replace more expensive, non-recyclable and energy-intensive synthetic fibers2,3 This is due to the recognition of various attractive attributes such as abundance, availability, renewability and low cost, together with increasing environmental concerns for the use of synthetic nonrenewable fibers. Despite attractive strength properties and numerous studies on reinforced composites, little has been reported on the use of ramie fibers in polyester composites. Ramie fiber composites are attractive structural materials for doors, panels, and furniture They could compete with other traditional lignocellulosic fiber composites for automobile components. Fiber infrared analysis and composites SEM fractographs disclosed the effectiveness of the fiber/matrix interaction

Materials

Methods

Density and Size Distribution

Ramie Fiber FTIR

Mechanical properties

Impact Properties